1. Field of the Invention
This invention relates to methods of treating vascular disease in diabetic patients.
2. Description of the State of the Art
Until the mid-1980s, the accepted treatment for coronary atherosclerosis, i.e., narrowing of the coronary artery(ies) was coronary by-pass surgery. While being quite effective and having evolved to a relatively high degree of safety for such an invasive procedure, by-pass surgery still involves potentially serious complications and in the best of cases an extended recovery period.
With the advent of percutaneous transluminal coronary angioplasty (PTCA) in 1977, the scene changed dramatically. Using catheter techniques originally developed for heart exploration, inflatable balloons were employed to re-open occluded regions in arteries. The procedure was relatively non-invasive, took a very short time compared to by-pass surgery and the recovery time was minimal. However, PTCA brought with it other problems such as vasospasm and elastic recoil of the stretched arterial wall which could undo much of what was accomplished and, in addition, created a new problem, restenosis, the re-clogging of the treated artery due to neointimal hyperplasia, that is, abnormal regrowth of the inner lining of the vessel after treatment with PTCA.
The next improvement, advanced in the mid-1980s, was the use of a stent to maintain the luminal diameter after PTCA. This for all intents and purposes put an end to vasospasm and elastic recoil but did not entirely resolve the issue of restenosis. That is, prior to the introduction of stents, restenosis occurred in from about 30 to 50% of patients undergoing PTCA. Stenting reduced this to about 15 to 20%, a substantial improvement but still more than desirable. For diabetic patients, however, the incidence of restenosis after stenting and major cardiac events were significantly higher than for non-diabetics patients.
In 2003, drug-eluting stents or DESs were introduced. The drugs initially employed with the DES were cytostatic compounds that curtailed the proliferation of cells that resulted in restenosis. The occurrence of restenosis was reduced to about 5 to 7%, a relatively acceptable figure. However, the rate of restenosis with DES is still higher for diabetic patients than non-diabetic patients. In addition, the use of DESs engendered yet another complication, late stent thrombosis, the forming of blood clots long after the stent was in place. It has been hypothesized that the formation of blood clots was most likely due to delayed healing, a side-effect of the use of cytostatic drugs.
Thus, there is a need for improved methods for treating vascular disease in diabetic patients.